''Charixena iridoxa'', also known as the Astelia zig-zag moth, is a

moth Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...

of the family

Plutellidae The Plutellidae are a family of moths commonly known as the diamondback moths, named after the diamondback moth (''Plutella xylostella'') of European origin. It was once considered to have three subfamilies: Plutellinae, Praydinae, and Scythropi ...

. It was first described by

Edward Meyrick Edward Meyrick (25 November 1854, in Ramsbury – 31 March 1938, at Thornhanger, Marlborough) was an English schoolmaster and amateur entomologist. He was an expert on microlepidoptera and some consider him one of the founders of modern micr ...

in 1916. This species is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

and has been observed in the North, South and Stewart Islands. The life cycle of this moth is at least two years in length with the larvae inhabiting the bulb of its host plants and mining the underside of its leaves. These mines have a distinctive zig-zag appearance and can be easily recognised when looked for on the host plants. The larvae pupate in a cocoon attached to the leaf and this stage takes place between February and August. The adult moths emerge in the early spring and are fast, day flying moths. Their larval hosts are plants in the genus ''

Astelia ''Astelia'' is a genus of flowering plants in the recently named family Asteliaceae. They are rhizomatous tufted perennials native to various islands in the Pacific, Indian, and South Atlantic Oceans, as well as to Australia and to the southern ...

'' and include '' Astelia fragrans'' and '' Astelia nervosa''.

Taxonomy

This species was first described by Edward Meyrick using specimens collected at Mount Burns in the

Hunter Mountains The Hunter Mountains of Lake Manapouri, New Zealand, were named by surveyor James McKerrow after the famous anatomist John Hunter. The Hunter Mountain Range covers an area between The South Arm and Hope Arm of Lake Manapouri South to the Green ...

and originally named ''Philpottia iridoxa''. In 1921 Meyrick, recognising that the genus name ''Philpottia'' was preoccupied, placed this species in the genus ''Charixena''. In 1924 Morris N. Watt published a paper giving details of the life cycle and describing the larva and pupa of this moth.

George Hudson George Hudson (probably 10 March 1800 – 14 December 1871) was an English railway financier and politician who, because he controlled a significant part of the railway network in the 1840s, became known as "The Railway King"—a title conferr ...

discussed and illustrated this species in his 1928 book ''The butterflies and moths of New Zealand''. The female

lectotype In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes the ...

is held at the

Natural History Museum, London The Natural History Museum in London is a museum that exhibits a vast range of specimens from various segments of natural history. It is one of three major museums on Exhibition Road in South Kensington, the others being the Science Museum an ...

Description

Watt described the larva of this species as follows: Watt also described the pupa and cocoon of this species as follows: Meyrick described the adults of this species as follows:

Distribution

This species is endemic to New Zealand. It is found from the middle of the North Island southwards including in the South Island as well as Stewart Island. This species has been collected in the Hunter Mountains, the Ruahine Mountains and on Mount Taranaki, at Mount Arthur and Arthur's Pass, in Otago, at

Lake Te Anau Lake Te Anau is in the southwestern corner of the South Island of New Zealand. The lake covers an area of , making it the second-largest lake by surface area in New Zealand (after Lake Taupō) and the largest in the South Island. It is the larg ...

and in Milford Sound. Mount Te Aroha forms the northernmost known location for this species. Although this moth is widespread as evidenced by the prevalence of its larvae feeding on ''Astelia'' species, observing the adult moth is rare.

Habitat and hosts

This species inhabits forests and in mountainous terrain, just above the tree-line, where its host plants are prevalent. The larval hosts of ''C. iridoxa'' are species in the plant genus ''

'' including '' Astelia fragrans'' and '' Astelia nervosa''.

Life cycle

The larva of ''C. iridoxa'' live below ground in the bulb of its host plant and takes at least two years to mature. It mines the underside of leaves of its host plant from within the bulb of the plant and the leaf mine becomes visible as the leaf grows. The leaf mines have a zig-zag shape and are distinctive in appearance. The larva will travel upwards on to the plant leaf to pupate within a cocoon formed inside a leaf. As this cocoon is attached to the leaf it will move away from the bulb of the plant as the leaf grows. This pupation stage takes place from February until August. The adult emerges in early spring. This emergence date may go some way to explain the comparatively few times the adult of this species has been observed compared to its widespread and numerous nature.

Behaviour

The adults of this species are on the wing from October to December and are fast day flying moths.

Reference

{{Taxonbar, from=Q13461800 Moths described in 1916 Plutellidae Endemic fauna of New Zealand Moths of New Zealand Taxa named by Edward Meyrick Endemic moths of New Zealand